Indicator for telephone switchboards



Oct. 25, 1949. c. LOMHOLT INDICATOR FOR TELEPHONE SWITCHBOARDS 2 Sheets-Sheet 1 Filed Oct. 11, 1947 INVENTOR. igr/Zamio/ BY ATTORNEY Oct. 25,1949. c. LOMHOLT 2,485,615

INDICATOR FOR TELEPHONE SWITCHBOARDS Filed Oct. 11, en -2 Sheets-Sheet 2 IN VEN TOR.

Byte/Z ATTORNEY Patented Oct. 25, 1949 UNITED STATES PATENT OFFICE INDICATOR FOR TELEPHONE SWITCHBOARDS Application October 11, 1947, Serial No. 779,318

1 Claim. 1

This invention relates to telephone switchboards and more particularly to an indicator therefor adapted to signal the operator when a subscriber desires to make a call.

An object of the invention is to' provide a compact indicator for telephone switchboards which requires very little board area and is not dependent on gravity for operation, but will operate regardless of the positioning thereof with respect to the force of gravity.

In accordance with this invention a feature thereof is the compact arrangement of the parts whereby they are housed in a slender tubular casing with the indicator element at one end. By mounting the tubular indicator so that the indicating element protrudes through the switchboard panel, the operator may be signalled when a subscribers line is connected through to the indicator device. The unit being tubular in shape extends behind the panel and requires a minimum of space.

Another feature of the invention is the control of the indicator element. The indicator element is mounted on a spindle and is normally biased to turn to indicating position by a spring. The spindle is held against operation by a crank arm engageable with an armature. When the electromagnet of the indicator is energized, the armature is attracted thereby releasing the spindle to turn the indicator element to indicating position. The spindle is provided with lateral extensions for engagement with a reset plunger whereby the insertion of a plug in an associated jack will cause the plunger to be actuated and thereby return the spindle to non-indicating position.

The above mentioned and other features and objects of this invention and the matter of attaining them will become more apparent, and the invention itself will be best understood, by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a longitudinal sectional View of the indicator and an associated jack;

Fig. 2 is a view in perspective of the indicator housings; and

Fig. 3, 4 and 5 are cross-sectional views taken along lines 33, 4-4 and 5-5 of Fig. 1.

Referring to the drawings, the indicator comprises a housing made up of two telescoping tubular parts I and 2. Part I houses an electromagnet 3, the coil of which is retained in place by core 4, block 5 and end plate 6. If desired a bracket 1 may be mounted on housing I 2 as shown where a contact pile is to be directly associated with the indicator. As shown, a contact pile B is mounted on the bracket 1. It will be recognized, however, that the indicator may be used independent of a contact pile and in that case the bracket 1 may be omitted.

The tubular part 2 houses the operating mechanism of the indicator. A bearing 9 is received therein and keyed to the housing 2 as indicated by pin W. A spindle II is received in the bearing 9, and carries on one end thereof an indicator element 12, which in turn is housed by a cap i3 threadably received on the end of housing 2. The cap [3 is preferably of molded plastic material having transparent window sections it separated by opaque or colored sections 5. The indicator element is provided with sections of alternate coloring as indicated at I6 and H, the color of sections I! being the same as sections I5 of the cap so that when they coincide with windows M as shown the cap appears all one color. When the indicator element l2 moves to indicating position the areas [6 either white or a color different from sections I! are exposed through windows 14.

The indicator element I2 is provided with a hub l8 which abuts bearing 9, the hub having a stop I9 for engagement with shoulders 20 on the housing 2 to limit the movement of the indicator element. The hub and the spindle are normally biased to move the indicator element toward indicating position by a spring 2| which has one end secured to the hub 18 and the other end retained in a slot 22 in bearing 9. The spindle is held in place in bearing 9 by a collar 23 which is press-fitted on to the spindle. The inner end of spindle H is provided with a crank 24 which is adapted to engage a recess in armature 26. The armature is normally biased to crank engaging position by a spring 21, the armature being retained on pins 28 and 29 which are anchored in block 5. Pin 28 limits the outward movement of the armature while pin 29 permits the armature to pivot.

When a subscribers line is connected electrically to the indicator, the electromagnet 3 is energized thereby attracting the armature 26 which thereupon releases crank 24. The spindle revolves under the force of spring 2| and causes the indicator element l2 to assume an indicating position.

For reset purposes the spindle is provided with a pin 30, Fig. 4, which extends laterally thereof and is engaged by reset plunger 3 1. Reset plunger 3!, is provided with a U-shaped portion having one surface 32 higher than the other surface 33. These two surfaces are utilized as follows: when the plunger 3| is lifted, surface 32 engages pin 30 to rotate the spindle to reset position, the surface 33 operating as a stop when the other end of pin 30 engages it. In this position of the spind'le -the crankafl is received in recess 25 and latched to the armature-26f In the embodiment shown the switchboard panel 34 is provided with a jack socket 35 in:

alignment with the contact pile 8., Theuppermost contact spring 36 is provided witl'i'a stud. 3.l.

adapted to engage stem 38 of the plunger 31.

Contact spring 353 which is adapted to beengaged" by a jack plug (not shown) is provided with a stud 40 which engages spring 36 to break contacts (which are closed by release of crank 24 4| through action of spring 2|, pin 30 and plunger 3|) and to actuate the plunger pin 38 to resetin-- dicator element I 2 andzlreturn the crank 2t to latching engagementwithzthe armature 26:

While in. the present embodiment the reset plunger is. shown' to be operated'by insertion of a jack'plugrinto the spring contact pile-up; it'will be obvious to those skilled in; the art that a. pushbutton arrangement may be. arranged to actuate they-plunger where-jack plugs and spring. contact pile-up' arrangements "are not employed in asso ciation with the: indicator: It will also be clear that while I have shown the housing made of two telescoping. parts I and 2Lit may be made in one part; The. present housing is made intwo parts to provide for a reducedisize at the panel end and toifacilitate assembling of parts;

The end of .housingr2; Fig. 3 is provided with recesses42-ar1d'43,' the recess being adapted to receive. a' key projection on panel 34 to retain the'indicator in a desired position, and the recess 43 to receive stop pin H9.

The indicator with cap I3 removed is received in an opening in the panel and secured thereto by applying the cap I 3 over the projecting end of 1 housing: 2. A threadedsleeve 45 is employed'to clamp'thesindicator to the panel.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation of the scope of my invention.

I claim:

An indicator for switchboards comprising a spindle, indicator meanscarried by said spindle to provide a signal indication when moved to a given position, a spring normally urging said spindle to turn for movement of said indicator means-to said given position, a latch to hold said spindle against turning movement, means to releasesaid latch when a signal indication is desired, a pin carried by said spindle and disposed transversely of'the axis thereof, a reset plunger having twonspaced portions, said portions and said pin being arranged so that upon actuation of said plunger one portion engages said pin to rotate said spindle and the other portion engages said pin to'limit'the reset movement of said spindle.

CARL LOMHOLT;

REFERENCES CITED The following references are of recorclin the file of this patent:

UNITED. STATES PATENTS 

